1. Technical Field
The present invention relates to an electrophoretic display device and an electronic apparatus.
2. Related Art
There have been known electrophoretic display devices each including an electrophoretic dispersion liquid containing a liquid phase dispersion medium and electrophoretic particles and using the phenomenon that when an electric field is applied, the dispersion state of the electrophoretic particles is changed to change the optical characteristics of the electrophoretic dispersion liquid (refer to, for example, Japanese Unexamined Patent Application Publication No. 6-203954). Such electrophoretic display devices may be decreased in cost and thickness due to no need for backlight. Furthermore, the electrophoretic display devices have a wide angle of view, high contrast, and display memory, and thus the electrophoretic display device attract attention as next-generation display devices.
A known example of such electrophoretic display devices includes an electrophoretic dispersion liquid enclosed in microcapsules which are held between a transparent substrate having a transparent electrode, for example, serving as a common electrode and a substrate having pixel electrodes. The enclosure of the electrophoretic dispersion liquid in microcapsules has the advantage that it may be possible to prevent flow out of the dispersion liquid in a process for manufacturing a display device and to decrease sedimentation and aggregation of electrophoretic particles.
On the other hand, a microcapsule-type electrophoretic device is disadvantageous in that when moisture or the like enters a microcapsule display layer from the outside, the electric conductivity of the display layer is increased to degrade the display function.
Therefore, in order to improve the moisture resistance of an electrophoretic display device, there has been widely used a method in which a waterproof film (waterproof sheet) is attached to the outer periphery of a body of an electrophoretic display device, for preventing the moisture entrance into a display layer of the electrophoretic display device.
For example, Japanese Unexamined Patent Application Publication No. 6-203954 discloses a method of bonding a back protecting material, by a vacuum lamination method, to an electroluminescence layer in which a transparent electrode, a luminescent layer, a dielectric layer, and a back electrode are laminated in that order on a light transmitting substrate.
Japanese Unexamined Patent Application Publication No. 11-236538 discloses a method of thermally pressure-bonding a hot melt film having a buffer adhesive layer, with a roll laminator or the like, to the upper surface (light receiving surface) of a laminated member such as a solar cell sheet and at least one of the surfaces of a resin base material having transparency and heat resistance.
In bonding a waterproof film to a body of an electrophoretic display device by the vacuum laminator or roll laminator method, constant temperature and pressure are applied.
When a display electrode is formed on a substrate, a certain space is provided between the display electrode and the peripheral edge of the substrate, for securing some degree of margin. Since the display electrode is not formed in the space, a step is formed by the display electrode.
When a waterproof film is attached to the periphery of such an electrophoretic display device body by the vacuum laminator method, temperature and pressure are applied to the electrophoretic display device body, and thus the substrate is deformed by bending due to the step formed in the space at the periphery of the substrate. The deformation of the substrate causes high stress to be applied to the peripheral portion of the substrate as compared with the other regions. Therefore, the microcapsules disposed in the periphery of the substrate are crushed to bring about the problem of causing a display defect in the periphery of a display region (refer to FIG. 9).